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Shortened design and lifetime of embedded systems has motivated active research in HW/SW co-design area, together with evolution of relatively long-life of reconfigurable HW. In this paper we present AKKA-a set of tools for design space exploration, co-simulation and co-synthesis with two industrial examples from the telecommunication field-Maintenance functionality of the ATM protocol and Channel decoder functionality of a D-AMPS base station. For fast prototyping we have selected Xilinx XC4013 FPGA based board from Virtual Computer Corporation. The board is connected to the system bus (SBus) of the host computer

This paper presents Hermes, a depth-optimal LUT based FPGA mapping algorithm. The presented algorithm is based on a new strategy for finding LUTs allowing to find a good LUT in a significantly shorter time compared to the previous methods. The quality of results is improved by enabling LUT re-implementation and by introducing a cost function which encourages input sharing among LUTs. The experimental results show that, on average, the presented algorithm computes 15.5% and 3.5% smaller LUT mappings compared to the ones obtained by FlowNlap and CutMap, respectively, using two orders of magnitude less CPU time. The speed of Hermes makes it suitable for running in an incremental manner during logic synthesis.

Power losses affect both the installation- and long-term cost of power electronic systems. The installation cost is related to the fatt that power losses in silicon power devices generate heat and make installation of heat sinks and water cooling necessary. If self-heating effects are strong, lotal overheating can eventually lead to device failure. To improve the design of power device systems, more accurate calculations of the Safe Operating Area (SOA) of power devices are desirable. Power semiconductor devices with lower losses are also needed. With the emerg ing SiC technology, much higher drift temperatures can be tolerated and much lower power losses can be achieved for the very high voltage range.

In this thesis, on-state losses in bipolar Si and SiC power devices have been studied by comparing measurements to numerical simulations. Carrier distributions under high-leve1 injection were mesured utilizing the technique of Free Carrier Absorption (FCA). Measurements were performed for elevated temperatures under static equilibtium for Si power diodes and Insulated Gate Bipolar Transistors (IGBTs). Potential distributions in power diode structures were meas ured by contacting the samples with a tungsten probe tip. A set of physical models for accurate simulation of bipolar Si power devices is proposed; special attention was drawn to the modeling of minority carrier transport in emitters. Measurements of carrier distributions were canied out also for 4H-SiC power diode structures and the results were compared with simulation. Physical models for simulation of 4H- and 6H- SiC bipolar power devices are suggested. It was found that anisotropic material properties are important for the operation of bipolar 6H-SiC devices.

Finally, various contributions to the heat generation term of a recently improved theory were evaluated under extreme, but realistic conditions. It was concluded that heat generation in bipo lar Si power devices, both stationary and transient, can be modeled accurately by only taking the Joule heat and the recombination heat terms into account.

Nonlinear effects are known to influence the propagation ofoptical waves in fibers already at modest power levels. Thisprovides us with a unique tool to observe nonlinear phenomenaunder comparatively simple experimental conditions and alsoopens the door to numerous important applications.

One of the most interesting nonlinear phenomena is theformation of different types of optical solitons - opticalpulses that can propagate in a dispersive medium withoutbroadening. Solitons play an important role in the developmentof ultra-high speed optical communications and in thegeneration and control of ultrashort optical pulses. Thistheses deals with different theoretical aspects of nonlinearpulse propagation and generation of optical solitons.

When sub-picosecond optical solitons propagate in a fiber,they experience a dynamic nonlinear response that gives rise tointrapulse Raman scattering. We analytically derived theself-frequency shift of optical solitons in such a medium andshowed that solitons continuously radiate a part of theirenergy into dispersive waves, which gives rise todelocalization of the optical wave.

Considerable attention in this thesis is paid to the theoryof soliton generation and propagation in nonlinear amplifyingmedia. The stability of the pulse generation in passivelymode-locked lasers with fast saturable absorption wasanalytically analyzed by using the complex Ginzburg-Landauequation. The same equation was employed to model modulationalinstability fiber lasers with intracavity Fabry-Perot filter,which generate a train of optical solitons at a high repetitionrate. By taking into account the effect of dynamical gainsaturation on the ultrashort pulse generation in lasers, wediscovered a new type of self-accelerating dissipative solitonsthat have a continuous frequency drift, but a stationaryintensity profile in broad band gain media. We also showed thatthe existence of self-accelerating dissipative solitons maylead to peculiar transient processes in the pulse propagation,such as self-tuning of optical solitons to the zero-dispersionpoint and periodic interconversion of optical solitons.

The fiber nonlinearity may also induce detrimental effects,for instance pulse-shape distortions that usually rise duringcompression of chirped pulses. We proposed a new method basedon time frame transformation for efficient simulation of strongcompression of chirped pulses in optical fibers.

Another interesting nonlinear phenomenon is the formation ofsaturation gain gratings in amplifying media. In the last partof the original research work in this thesis, we developedmodels for RE-doped DFB fiber lasers that include the effect ofsaturation gain gratings and pump depletion and showed thatthese effects significantly influence the laser performance. Wealso derived an analytical expression for saturation gaingratings in amplifying media with arbitrary diffusion rate ofexcited states. This solution constitutes a "bridge" betweenthe two known limiting cases of week and strong diffusion, andprovides a useful tool for correct analysis of single-modelasers.

The effect of crosstalk noise becomes increasingly significant as geometries continue to shrink into the deep sub-micrometer regime and clock frequency increases into the multi GHz domain. Dynamic delay caused by coupling capacitance between adjacent interconnections is a critical problem, as it cannot accurately be estimated in static timing analysis. This paper presents a new driver circuit scheme called the Crosstalk Immune Interconnect Driver (XTIID), for capacitively coupled interconnects, which eliminates pattern-dependent coupling noise. Also, such an interconnect drive technology has the potential to facilitate the dynamic timing problem in deep submicrometer VLSI design.

This thesis treats electron-waveguide devices bothexperimentally and theoretically. A fabrication method forelectron-waveguide devices with trench-isolated in plane gateswas developed in the In0.53Ga0.47As/InP material system. The two dimensionalelectron gas was grown by metal-organic vapor phase epitaxy.The pattern, defined by electron-beam lithography, wastransferred to the electron gas by a deep dry-etchingprocedure. For the first time, to our knowledge, indeeplyetthed In1-xGaxAs/InP, this method achieves conductancequantization demonstrating the quality of the electronwaveguides.

The mechanism behind the gating for these devices wasinvestigated by measuring the current through the device as afunction of the voltage on the two side-gates and comparing theresult to a numerical self-consistent calculation. for thiscomplicated geometry. The gating was mainly mediated by theetthed surfaces, on which the potential was calculated byassurning a small leakage current. The Schottky character ofthe interface between the etthed surfacc and the electron gasesexplains the nonlinearity where a negative gate voltage affectsmore than a positive one.

The same basic design was employed in a Y-branch switch(YBS), where an electric field between the gates deflects theelectrons into either of the two branthes. The entireconductance matrix was measured in a systematic way and agreedwith a criterion for coherent single-mode transport.

Also, measurements on four-port cross structures of varyingsizes were done. It was found that for sufficiently smallstructures and for low source-drain volt ages, the electronsare more likely to trave1 ballistically, straight through thedevice, than to be scattered into a side arm, even at roomtemperature.

The high-frequency properties of single-modeelectron-waveguide devices were studied theoretically in termsof plasma-wave propagation using a semi classical approach,which allowed the calculation of boundary conditions at discontinuities such as the junction to the reservoirs, ascattering center, and a multiport connecting a number ofwaveguides. A transmission-line analogy was developed for theplasma-wave or signal scattering, useful for the microwaveengineer. This was in turn used to calculate the high-frequencyadmittance measured between the reservoirs of an electronwaveguide.

Finally, a novel operation mode of the YBS was proposed,where the switching is controlled by the potentials in thewaveguides. In this self-gated mode, the YBS was predicted tooperate at higher frequencies because of the absente of gatesand the associated high RC-constants, and on lower voltagesbecause of the more efficient gating mechanism.

The use of optical fibers and optical network componentsallows aggregating the bit streams in order to minimize theequipment that is necessary for transmission and switching. Inthis way, however, the robustness of the network totransmission failures is decreased, i.e., number of servicesthat can be affected magnifies the effect of failure.

Thus, the reliability issues are of great importance inattempting to introduce photonics in a broader context incommunications, e.g. for cross-connects, ATM switches etc.These questions are becoming of high significance with theimminent introduction of more photonic functionality in thenetworks and have received scant attention in the past.

The aim of this thesis is thus to investigate reliabilityperformance of optical switching nodes in order to define theirusefulness for application in high capacity telecommunicationnetworks. The work has been focused on demonstrated nodearchitectures. The limitations of these architectures have beeninvestigated, originating from reliability data for optical,electro-optical, and opto-mechanical components.

The introductory part of the thesis describes the researchtopic, aim and motivation for the thesis project, basics forsystem reliability modeling and summarizes the originalresearch work. The main results are presented in sixpublications, which are reproduced in the thesis.

In this thesis the reliability performance of severaloptical ATM switches and optical cross-connect nodes has beeninvestigated. Some original solutions have been proposed bothfor the node architectures and, for the choice of components inorder to improve the reliability of the switching nodes.

It is shown that all of the considered photonic ATMswitching systems have to be modified in order to meetreliability and performance requirements. The improvement ofthe reliability performance of photonic ATM switching systemshas been investigated. It is shown that for the configurationsconsidered, introducing inherent redundancy is not enough andproviding a multiplane structure is required in order tosatisfy the reliability and ATM service standards.

Considerable attention is paid in this thesis to the opticalcross-connects (OXCs) because they are considered as imminentand basic optical networking elements, allowing morefunctionality to the transparent optical networks. The OXCsstudied in this thesis are characterized by differentarchitectures and component technologies.

It is shown in this thesis that in most published cases, thereliability performance is very far from that requested, in theproposed configurations. A novel strictly non-blockingarchitecture of the optical cross-connect has been proposed inorder to improve the reliability of the optical cross-connectnodes to an acceptable level.

Silicon carbide (SIC) is a wide bandgap semiconductor thathas been suggested as a replacement for silicon in applicationsusing high voltages, high frequencies, high temperatures orcombinations thereof. Several basic process steps need to bedeveloped for reliable manufacturing of long-term stableelectronic devices. One important process step is the formationof an insulator on the silicon carbide surface that may be usedas a) a gate dielectric, b) for device isolation or c) forpassivation of the surface. Silicon dioxide and aluminumnitride have been suggested for these purposes. This thesiscovers the investigation of some formation methods for boththese materials on 4H and 6H silicon carbide, and theelectrical characterisation of the resulting films.

Commercially available n-type and p-type 4H and 6H SICwafers have been used, and both the silicon face and the carbonface have been investigated. Silicon dioxide has been formed byseveral methods: a) dry thermal oxidation with or without theaddition of TCA (trichloroethane), b) wet oxidation inpyrogenic steam or with awater bubbler, c) oxide deposition byPECVD (plasma enhanced chemical vapor deposition) or LPCVD (lowpressure chemical vapor deposition) and d) oxidation of aevaporated or LPCVD deposited sacrificial layer of silicon. Theinfluence of various cleaning methods prior to oxidation hasbeen studied, as well as post-oxidation and post-metallisationannealing. The aluminum nitride films were grown by MOCVD(metal organic chemical vapor deposition) under various processconditions.

Oxidation kinetics have been studied for dry thermaloxidation at 1200 0C. The redistribution of aluminum (p-typedopant in SiC) during dry thermal oxidation has beeninvestigated using SIMS (secondary ion mass spectrometry). Themorphology of the aluminum nitride was determined using x-raydiffraction rocking curves, RHEED (reflection high energyelectron diffraction) and AFM (atomic force microscopy). Thequality of the silicon dioxide used as gate dielectric has beendetermined using breakdown field measurements. High frequencycapacitance-voltage measurements have been used on bothinsulators to a) verify thickness measurements made with othermethods, b) to determine fixed oxide charges by measuring theflatband voltage shifts and c) to quantitatively compare theamount of interface states.

An optimal total solution for radio and mixed-signal system integration needs tradeoffs between different design options. Among various design metrics, cost and performance are probably the two most important factors for design decisions. In this paper, we review and analyze cost-performance tradeoffs of system-on-chip (SOC) versus system-on-Package (SOP) solutions for radio and mixed-signal applications. A new design methodology, which quantitatively predicts performance and cost gains of SOP versus SOC,is presented. The performance model evaluates various mixed-signal isolation techniques between sensitive analog/RF circuits and noisy digital circuits in SOC or SOP. The cost analysis includes new factors such as extra chip area and additional process steps for mixed-signal isolation, seamless integration of "virtual components" or intellectual property (IP) modules, yield and technology compatibility for merging logic, memory and analog/RF circuits on a single chip, and extra costs for moving passives off chip. In addition to these, a complete and systematic analysis method for on-chip versus off-chip passives tradeoffs is presented. The analysis and modeling techniques explore tradeoffs between performance, cost, robustness, and yield when different on-chip or off-chip passives are used. It thus provides a complete picture of quantitative tradeoffs for using on-chip or off-chip passives. The design methodology and analysis techniques are then demonstrated through several design examples in wireless applications. It is clearly shown that for all complex and high performance mixed-signal systems, SOP is a lower cost solution than SOC. Finally,some design guidelines for SOC versus SOP and on-chip versus off-chip are concluded.

Emerging wireless applications for logistics, intelligent home networks, smart dusts, wireless body area networks (WBAN) will need integration and fusion of a diversity of technologies, which may include digital CMOS circuits, analog/RF circuits, sensors/MEMS, embedded software and memories, antenna, displays, polymer, packaging and interconnections, new materials and new integration process. System-on-package (SoP) is considered as a promising solution for the fundamental integration platform for such applications. In this paper, we show how SoP technology can address the integration platform for these applications and how this can be done in a better way than system-on-chip integration. We first demonstrate the integration process of, SoP in liquid-crystal polymer materials. We see that liquid-crystal-polymer is a promising material for low cost RF SoP. We then demonstrate some design examples. The first one is an integrated 5GHz RF receiver front-end in liquid crystal polymer. Due to high quality of passive components in SoP, superior RF performance is found in this module. In the second example, we address several critical design issues for on-chip versus off-chip passives in a multi-band multi-standard radio for beyond 3G applications. We find that not only RF performance can be improved. Cost benefits are also obvious for such a complex radio. Chip-package co-design for smart parasitic absorption is demonstrated through an RF module for an ultrawide band radio in gigabit wireless. Concept of a SoP pacemaker in a WBAN is shown. Finally, we discuss some system level integration issues and we show how a system can be smartly partitioned for SoP so that we can obtain an optimal total solution for low-cost and good-performance wireless integration.

A rule based allocator for improving synthesis of filter systems is presented. The principles of the Enhanced AIlocation Rule Language Interpreter (EARLI) are presented. Possible transformations, optimisations and how to express them in EARLI are discussed. Experiments show that relative area gains ranging from 5 to 44%, depending on the chosen target technology, can be achieved using the designers knowledge about the design class. Experiments also indicate that employing direct mapping of CDFG subgraphs onto preoptimised RTL-level macroblocks would have resulted in a relative area gain of 500%. The macroblock had only 16% of the area produced by the HLS-tool

For a synthesis methodology to support implementation independent design specification, a capability for design space exploration is essential. In this paper we present such a methodology for a specific domain: data communication protocols. A natural way to specify various elements of protocols is in terms of a grammar annotated with actions. Our language for protocol specification, called PRO-GRAM, is based on this idea. The hardware specification of the protocol is done by specifying the bit-patterns of the tokens the protocol is supposed to parse together with the actual grammar to parse the input stream. By specifying constraints on the input and output stream ports, the designer is allowed to explore alternative realisations with different widths of the I/O ports. The PRO-GRAM compiler outputs VHDL-code suitable for logic synthesis

We present a grammar based specification method for hardware synthesis of data communication protocols in which the specification is independent of the port size. Instead, it is used during the synthesis process as a constraint. When the width of the output assignments exceed the chosen output port width, the assignments are split and scheduled over the available states. We present a solution to this problem and results of applying it to some relevant problems